1. Field of Disclosed Apparatus
The present disclosed apparatus relates downhole hydraulic jet pump assemblies.
2. Description of the Related Art
The in creased world-wise use and demand for oil and gas has generated a need for the retrieval of oil and gas from underground locations. Therefore many advances have been made in increasing the efficiencies and lowering the costs in removing oil and gas from subterranean formations.
In a typical oil and gas recovery process a steel tubular casing, extending the length of the well, is inserted into a drilled well and uncured concrete is pumped down the casing. Upon forcing of the concrete out of the bottom of the casing, it fills an annular space between an outer surface of the casing and the walls of the well, where the concrete cures to firmly anchor the casing to the well walls and seals off the well. To access the oil or gas through the now sealed well casing, the casing and the concrete are perforated at a downhole depth adjacent to the oil or gas subsurface formation. These perforations allow the oil and/or gas fluid to enter the well casing from the formation for retrieval. Due to the difference in pressure between the formation and the well casing interior, the inrush of the fluid into the well is substantial enough to clean the perforation passages of any debris for unobstructed passage of fluid into the casing.
In some regions, such as in the Middle East, sufficient bottom hole pressure, via natural gas, often is available in the formation to force the production fluid to the surface, where it can be collected and utilized for commercial purposes. As the localized natural gas in these drilled formations begin to deplete, various techniques are utilized to continue oil and gas production from the wellbore, these techniques are known in the industry as artificial lift. The artificial lift methods will require the insertion of a smaller jointed steel pipe into the original casing typically referred to as tubing. One such artificial lift technique employs the use of produced natural gas, this production method is referred to as gas lift. The produced natural gas and associated apparatus are employed to inject gas into the production fluids to assist lifting of them to the surface. This gas injection typically involves inserting a smaller diameter jointed gas lift tube into the well casing. The gas lift tube includes a plurality of perforated gas lift mandrels formed for discharging gas. As the gas passes through the mandrels and into the production fluid in the annulus formed between the casing and the jointed tube, the gas mixes with, and is entrained in the production fluid, causing the density, and hence the column fluid weight or gradient, to decrease. This lower weight enables the current, lower, down-hole pressure to lift the production fluids to the surface for collection.
In time, however, water seeps into or permeates the well column, which eventually impedes or prevents removal of the production fluids through gas lifting techniques. Traditionally, water is removed by purging the well with nitrogen. Purging is typically performed by inserting coil tubing into the jointed gas lift tube which coil tubing includes a one-way valve situated at the lower or distal end thereof. Nitrogen gas is discharged through the valve which exits the coil tubing at a sufficient pressure and rate to purge the undesirable water from the annulus. This purge permits the formation or production fluids to enter the annulus through the casing perforations for lifting to the surface.
While this technique has proven sufficient to remove water from the well column, the costs associated with operation can escalate. This is primarily due to the amount of nitrogen gas which must be discharged from the coil tubing, which is substantial. Other gases may be employed for purging but nitrogen is inert and available.
In some instances, a more cost-effective approach than the use of nitrogen purging may be used. A hydraulic or down-hole jet pump can be attached to the end of the tubing and lowered into the well casing to pump water and/or production fluid from the column. Hydraulic or down-hole jet pumps are often favored over mechanical-type pumps in situations such as de-watering of wells or production fluid pumping. Briefly, jet pumps generally include a power fluid line operably coupled to the entrance of the jet pump, and a return line coupled to receive fluids from a discharge end of the pump. As the pressurized power fluid is forced, by a pump at the surface, down through the down-hole jet pump, the power fluid draws in and intermixes with the production fluid. The power fluid and production fluid (oil and/or gas) then are pumped to the surface through the return line, and the production fluid may then be recovered, together with the power fluid. Jet pumps are often advantageous since they generally involve substantially fewer moving parts than mechanical pumps, thereby increasing the reliability of the jet pump.
The presently disclosed apparatus relates to a hydraulic jet pump comprising: a nozzle housing; a nozzle member disposed within said nozzle housing and including an inlet aperture communicating through a jet nozzle with a mixing chamber along a power fluid inlet flow path; a deflector member including an axial bore formed partially therethrough from an input aperture at a first end thereof towards a second end thereof, said input aperture communicating with said mixing chamber, said deflector member further including a plurality of radially-disposed deflector outlet ports communicating with said axial bore and disposed at an acute angle with respect to said input aperture to form a flow path having an output flow direction disposed at an acute angle with respect to an input flow direction from said input aperture, said deflector member further including a plurality of axially-aligned vacuum inlet ports formed therethrough from said first end to said second end and in communication with said mixing chamber but not with said deflector outlet ports.